[math-fun] Mathematical coloring book

Check out http://jdh.hamkins.org/math-for-seven-year-olds-graph-coloring-chromatic-num... Does anyone know of any other good mathematical coloring books for kids? (Personally I think almost any interesting schematic mathematical image, such as a hypercube or a picture created with a spirograph, could be fun for a kid to color. The choice of colors wouldn't necessarily have any mathematical significance, but coloring a number of such sketches over time could gradually shift a child's esthetic in mathematical directions.) Jim