You can paint them while they are on the car (not something I would do personally).
When you pull them off the car, they will stretch and bend so they can not be used again. So you will need new ones and I think I remember someone saying they are £25 for the full set. They are held on with strong tape and have mounting points to keep them straight.
So buy some new from the stealers, paint them yourself with rattle cans (seems a good enough finish tbh) and stick them back on.
The rough texture of the strips will need to be sanded down smooth. That can be done with some fine grit sand paper. Just prime them, spray them and stick them back on.
You could pay someone to do it at a bodyshop but, is it worth it? You can do it yourself and it would look fine. But you'd have to be good enough with a spray can.