I think this could be a fun game of memory with a couple more levels! Was nice to go through the level with a drawing tablet at my disposal.
I do think having a way to immediately go to the next coloring phase would be nice - it didn't take too long to color in a segment, so I'd have to wait for a while, usually.
Also, something that I think is pretty important is to add something that says you need to press enter to start the game - it took me a while to figure that out, and I was tempted to just quit the game before figuring that out.
Glad I did end up figuring that out though - this was a neat, relaxing experience!