When painting figures (for example, from 1 to 10) it develops a color perception, fine motor skills, attention, diligence and accuracy, mathematical ability. Such tasks are connected to the process logic of painting, allow to fix the basic math skills or letters.
Today there is a large set of coloring books. You can find coloring-cursive books, books outliners, for boys (all sorts of appliances, machines, robots, etc.), for girls (fairy-tale characters, dolls, funny funny little animals). There's even a wallpaper coloring books that opens a wide field to have enough space for young artist.