My brother is a Chameleon

This is a children's book about accepting people and their differences. The narrator's name is Amelia and her little brother has autism. Due to his condition their father did all the father and son activities with her. The Dad buys her a pet chameleon, that winds up indirectly showing Amelia whom them shows her father how to use color swatches or colors as method of speaking to the nonverbal son.