If all else fails, grab a can of Duplicolor Vinyl and Fabric coating. Auto parts stores usually have it. This stuff is wonderful for coloring all sorts of stuff that paint won't work on. You may have to recoat every few months or so, but the black covers up just about anything. It also comes in a variety of colors to match most soft parts I have seen.
Only one that might not work is the red. I've used that on snake print vinyl and it showed the scale coloring through it. The black, blue, charcoal gray, and burgundy all cover completely. Sorry...those are the only other colors I have needed to try so far.