Try to use a themed coloring. For example, a series of coloring books about animals, buildings or machines give children an idea of the objects of the world. Coloring of fairy tales or cartoon characters, are good because they allow the child to "talk" with their favorite characters and express their attitude towards them through colors.
Basically coloring designed for children from 4 years. It is necessary to offer the child a few options for the different colorings. It happens that some of them are out of child’s interest, while others will love it. So try to pick up the coloring in accordance with the interests of your children.