A colouring book is read as creativity within given lines — childhood comfort, calm and gentle rules. Dream books link it to a wish for simple, soothing tasks, or to feeling you must stay inside outlines drawn by others.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.