To see or colour in a colouring book symbolises childhood. It indicates that you have a carefree attitude, free from any responsibilities. On the other hand, the dream may be warning you against being idle and wasting time on fruitless pursuits.
Consider the significance of the colour you are using and what you are colouring. What is depicted in the colouring book suggests that you need to be more expressive in that area.
*Please See Also Crayons.