The automatic color coding of new members to a group sounds like a good idea at first. But what about the situation where the new member being added to a group also belongs to another group and is color coded for that group. should the member be changed to the color of the new group, or should the member retain the color of the first group?
Also as several people on this form have indicated, they use color coding for various tasks/reviews/purposes and that when they move on to a different purposes/task/review, the color coding is changed when they finish the first purpose/task/review and identify the people that are part of the new task/review/purpose. The people that are a part of any of these tasks/purposes/reviews may also be part of one or more groups that have in the past had color coding applied to the group.
It seems to me that making the color coding change automatic could likely lead to unintended consequences. I would think that thus the automatic color coding change should be an option to be made by the user and this option should be able to be changed at any time.