That is smartmmm depending on the sole material maybe. It's been years since I've worn toms... I liked them. I remember the size was particular though. Might have been a 7.5.
Discussion
Even if that turns purple it’ll probably rub off after a few walks which I guess is fine. If you’re really gonna customize it I’m sure one of the people that makes the custom hypebeast sneakers can add purple soles for you.