You can colour it with crayola wax crayons, but you'll need white to go under the pink you choose, to blend them together and get just the right colour. You colour with white, add the pink on top, then iron it with paper towel between the fabric and the iron to melt and take the extra wax out of the fabric. It will make it a little bit stiff, but that shouldn't matter for a wall quilt. I've attached a picture of a series of cats that I'm colouring. The pink striped front of the cat on the left is an example of what I'm talking about. It is both the same pink crayon, but with white under every other stripe.