Probably the easiest way to get a hold of pages for your kids to color is to print them out from websites online. There are plenty of sites that offer free downloadable coloring pages. Just search for "Christian coloring pages" or "Biblical coloring pages" in your favorite search engine, and you will find a bunch of results.
Give it a try! Print out a few Christian coloring pages for your kids and see how they respond. It is a great way to keep them thinking about the things of the Lord.