God bless you with the patience you will need! My sister workes with low functioning adults.she has a batchlers and loves her job, but still comes home stressed some days.I would sudgest a story before coloring and that way you could focus what some of the higher functioning are coloring.Give each one a part of the story show the pictures in the book some may want to draw what they see and others may want to draw what they imagine the picture would be. and again Gods blessings be with you!