I purchased an app called Colorizit from the Ovi Store.
N8 | Candy store
Colorizit is a Qt application. The interface is simple and fun to use. However, it stops working if the screen is rotated and crashes the phone if started in landscape mode. I think it would be easier to color if I had a pen instead of having to use my finger. You can zoom wide to color large areas or zoom in real close to fill in details. Very much worth the $1 I spent on it.