According to this site, one good thing for an intern to do is to invite a senior member to coffee and learn from their skills. This sounds a bit unusual. Is it really good advice?
Sure, it's risky but you you also have the potential to earn reward from inviting someone to coffee. In fact, I would highly suggest it if you were looking to improve yourself using the advice from someone who is experienced in the area you are interested. I have done something like this when I started searching for a new career, and it was a great way to see what was out there in the world and figure out whether a job or role was suitable for me. It is a good method to stand out from the crowd and show that you are motivated and interested. My response rate for job searching this way was nearly 100% versus practically 0% from plain online resume submissions.
If you do take someone out for coffee, be prepared to ask them questions. One of the worst things you can do is make the conversation entirely about yourself. That will put you in a negative light. A more receptive way to open up the conversation is to pose a topic and ask that person about it. Try to find something actionable that your invitee has done. More power to you if you had already researched the person's background. The more specific you can be, the better. If you ask a vague and general question, guess what, you will receive a vague and general answer. Your end result in inviting this person out is to create a personable impression and value for that person.
Even more important is to follow up periodically with your invitee. Thanking them is just one step (and I would do this the same day of the coffee arrangement), but sending a message periodically every so often will also strengthen your image in that person's mind. When you solicit advice, you better listen and act upon it and let that person know what happens. Continue following up with that person but understand that each follow-up does not necessarily have to prompt a response. It should also go without saying that you do not want to incessantly contact that person and create too much correspondence.
Remember that what you're doing is establishing a two-way street. Someone is giving up their time and energy and whatnot to devote to you, and it would be in your interest to return the favor and do the same. You are paying respect to what has been given to you instead of just taking from that person. When you do take someone out to coffee, you should definitely offer to pay since you initiated the meeting. If you two are arriving separately and the other party already grabs something, then don't feel bad about not offering.
The worst thing that could happen is that the person says no and turns down your invitation. Get that into your head as much as possible, because it will definitely help you overcome any mental barriers and fears you have about inviting some random stranger to coffee. The second worst thing is that you create a bad impression when you meet someone for coffee. Don't dwell on it; learn from your mistakes, find out what you can do to improve and how, and move on and try again.
I found the quote "Invite colleagues to lunch or coffee and find out why they are successful". It doesn't say senior. Therefore this would be full time people you have been working with while an intern. This is not too much of a stretch. If they are going to be working with you, some of them are likely to give you advice.
It is good advice to find a mentor. Some companies even have official mentoring programs. You are just making sure that you use some of the time you are an intern to take advantage of some of the mentoring opportunities.
I would make sure you recognize that different people will interpret this request differently. You're likely to get a range of interpretation from earnest naivete all the way to blatant sycophancy.
Like mhoran alludes to, I would start with the folks that you have more regular interactions with and save the more senior people for another time. As long as you're sincere, most people would be more than willing to spend an hour over lunch discussing things with you. Just make sure that you have some specific questions and topics to cover. If the crux of your questions are "How can I be successful at Company X?" you're odds of getting something beyond "Work hard and get your stuff done on time" aren't going to be that high, unless you get really lucky with the person you select. Think about what you want to get out of the exchange before you even broach having the exchange.
One place to be careful is when the person who is very senior to you is of the opposite sex. You do not want to come across as being sexually available and there are managers who would interpret this that way in my experience. (fewer than there were when I was young, but the scumbags are still out there.) Nor do you want your co-workers to think you are having an affair when you aren't. In a case like this, it might be better to get another intern to come with you and both of you ask questions.
So long as you are not pesky about it then the answer is It is not risky. If someone does not have time, or inclination, they will either tell you no or blow you off. Accept that response and move on. If you do that then chances are the that should the colleague decline chances are they will not give it a second thought.
If they accept it is important to be gracious. Offer to pay, but accept their offer should they insist on paying. Be prepared with good questions. If you want to ask them questions make sure that you can not get the answer by Googling, and try to answer the questions you can by yourself before you ask.
From personal experience, I worked at an internship which organized a meeting with the senior people in the company every two weeks. I'd bring the idea up to the HR rep and ask if they could help you set up the meetings. Instead of going out to coffee, it would be about 45 minutes in a meeting room, where they come and chat about themselves then you ask some questions. It generally is really good for interns, and I feel like most intern