Here is a Google Doc sub handout you can find at: No Corner Suns.
Another easy way to prepare for an art sub is to go to my shop, Art Sub Plans. I have created complete lessons in which all your sub has to do is read the slides and follow the directions. They are full of visuals and are created to be used with the most simple supplies. Pencils, paper and crayons are all your students will need to create imaginative works of art.
These are perfect for those emergency absences when you do not have the time to write detailed plans but want to leave quality plans for your subs.