Only paint them if you can do a good job - nothing looks more shabby than calipers painted with a brush, with drips and bits missed. Only the chavs do that. (Is 'chavs' the right word!?)
If you want to be super cool, get an old pair, mill a flat area on the casting and spray an Abarth scorpion on, then clear lacquer powder coat over the top. That would take time and skill though...
Here come da judge...