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.
If you really want to get right down to it, adults love to color as much are their kids do. If you dont believe us, think about all of the artists that do oil and watercolor paintings, those that do pen and ink drawings and watercolor pencil drawings and artwork. This is simply the more appropriate and acceptable way for adults to continue coloring as we all did as kids. This is partially why both adults and children alike really enjoy having SpongeBob printable coloring pages available to them to color on.