This is a very simple plugin we created ourselves that will display a little “badge” below each comment with the user’s role and for non-users it will display a badge that says “guest”. The plugin works with every default role (administrator, editor, contributor, author, subscriber) and it will even be added for custom roles (styling included already for the WooCommerce Shop Manager and Customer roles). The plugin hooks into the “get_comment_text” WordPress filter so it should work on any theme!
This plugin will load a stylesheet that adds the various colors to the badges. To alter the colors you will have to use custom CSS. Adding extra bloat for an admin panel or customizer settings seemed a bit too much for such a plugin that’s intended to accomplish such a simple task.