The lines of your coloring page are the rules you need to share with your team, share with them the boundaries. They are more likely to stay with in the lines if they know that they exist. Next by holding the work up for group and team acceptance they become their own self policing force. They can set self expectations and make constructive self criticism as well. The reward is acceptance and recognition from the team, an old saying is that a person can starve without any feedback, but only needs one good compliment to be filled to overflowing.
This will help them to not only recognize different colors but to also learn the names of the different colors. Developing these skills will help in later development too as your child begins to learn to read and write. He or she can then learn how to write the names of all of the different colors. You see learning is progressive and incremental - it happens in stages. Step-by-step as I have described. This is the true beauty of learning...the more that your child puts in, the more they will get out of learning. As their knowledge grows, so will their interest in a range of different subjects.