That won't work, paint can't flex much without cracking. I would also think the silicone by it very nature won't accept the paint. On the other hand what have you got to loose by painting the one you have, if it doesn't work sowhat, wipe it off. :dance:
Paint it!! I would try a vinyl dye from a auto paint store and probably black will work the best. More than likely you're stuck with a gray smoothie, drop the money and buy a macthing set as your time painting and trying stuff will cost more than just buying a new set.
I wouldn't waste my time come to think of it as whatever you use it's gonna wear off and look like ca-ca.