I needed to change the color of a couple of jacks for a project I'm working on. I thought about using spray paint but was worried that it would cause too much of a mess inside the jack itself.
I ended up using a Sharpie paint marker, which worked like a dream. Really fast and easy, with hardly any drying time.
If you're the sort of person who wants to color code your I/O, pick one up! Just be sure to paint the jacks before you install them (helping hands are, excuse the pun, very handy for this sort of thing)...