i would not dye it it would turn into a big mess, only cause dying will need rinsing
here are my votes, but they will take experimentation (depending on where it is and if it's a high traffic area) if you were going to use dye anyways, you wouldn't want dye to rub of on clothing.
- find a marker that matches it, if it's that much of an eyesore get some markers the ones with every color of the spectrum or buy a few artist ones and blend it in.
- colored pencil might work but it'll rub off more
if you really don't want it, you'll really have to experiment, I think
i think the best you can do is cover it up with pigment but again if it's on a place where clothes can get to it, its safer to just leave it.