Full disclosure: I am a high-functioning autistic.
I'm going to offer a few ideas that will benefit the greater workforce as well as the autistic employee, that way, everyone benefits.
Since autism is a spectrum, it varies, but:
- Don't call anything a "safe space", it's insulting. We don't need safety, we need a good work environment.
- Lights that don't flicker (e.g. high quality soft LED lights or incandescent lights) are a BIG PLUS. Many autistic people can sense the flickering of some lights, and it is as annoying as a buzzing, flickering one would be to you. LEDs can be full spectrum, and, including the "daylight blue" will help your other employees, as that is the wavelength that keeps us all awake.
- Any environment free of loud, sudden noises is also good.
- Anything standardized that doesn't change, or doesn't change often.
- Well defined policies and procedures
- Clearly defined work duties.
- The noise cancelling headphones are an EXCELLENT idea, and again, other employees would benefit.
- Anything to limit stimulus.
- Scheduled breaks
- The quiet room you described does show insight. Personally, I often run to the bathroom to reset. A room where you could just veg for a few minutes would be great too, and I imagine more than the autistic folks would benefit.
Perhaps the biggest insight I can give you is that the world itself is not made for us, an is uncomfortable, and is uncomfortable in such a way as to not be understood by people who are not on the spectrum.
Imagine, if you can, the color orange being painful, and every time you saw it, it felt like someone kicked you. Even when you know you're going to see it, you still feel the kick. Then, people around you are wondering why you are making such a big deal about the color orange. You, of course, not knowing that other people don't feel pain when they see orange, are going to wonder why you are so weak because they don't react to the pain they must be feeling, while telling you to stop making such a big deal of it.
So, yes, trying to understand it is a great help. Just knowing that the effort is being made, makes us a bit more at ease.
EDITED TO ADD:
I've seen the analogy of an autistic mind being like a train, where as an Neurotypical mind is more like a car.
A train can pull quite a bit of freight, and at a high speed, but if you try to take a sharp turn, you are in trouble.
Similarly, you wouldn't want a car pulling 20 box cars.
It's about knowing how to utilize the people. Just like everybody else, we do some things well, and some things poorly.