It is done by adding layers

The next step is to add the textures and begin to lay in areas of color and pattern. The director's shirt has been finished, using green to compliment the pink script. The actors clothing begins to develop, using a combination of warm patterns in the foreground and cooler darker patterns in the background. Two additions from the previous stage include one of the producers working on a lap top (she is to the extreme left in front of the grip) and a ladder in the upper left to help hold the weight of all of the actors in the lower right. At this point there is only the coffee cup to represent craft services, but it is enough to reflect their all important function on a film set. Robert's face (extreme lower right) isn't there yet. It definitely needs more work.