"To follow the colours" means to obey or follow the leadership or instructions of a person or group. It often refers to being loyal or supportive in a military or team context. Full definition
When choosing an accent colour or a mixed palette, you can't go wrong by following colour theory. (idealhome.co.uk)
Warm up a neutral bedroom by painting a bold red feature wall behind the headboard, then follow this colour through with select accessories. (idealhome.co.uk)
Red is the main colour for most menus, with black and white as highlights — even the school uniform follows this colour scheme. (thatvideogameblog.com)