What is Colouring ?
Colouring is (noun) 1. the way in which something or a plant or animal is coloured the bright colouring of parrots The brilliant colouring of woods in autumn. 2. complexion, the colour of your skin and hair Choose a lipstick that goes with your dress and suits your colouring. (NOTE: [all senses] The US spelling is coloring.)
source: Easier English, Student Dictionary Upper Intermediate Level