A theatre group can agree to wear items of clothing of one color or several colors during an appearance For example, it is common (also for musicians) to appear in all black. Black has the advantage that the "physical" person "withdraws" behind that, what is presented by their performance. Black has the disadvantage onstage that the actors cannot be seen very well with the light and black background. Also possible are coordinated color combinations, like, for example, black pants and red tops. With a coordinated clothing design you can have the group name and possibly a logo printed on the top (shirt/T-shirt). One can also naturally agree to be united in NOT appearing in coordinated colors, if necessary even in their everyday clothes.
Very colorful or even extravagant clothes have the disadvantage that they distract too much from the scene.