A group of people, one of which is a woman with a large white and colorful purse, wait to board a large white and blue bus.
A group of people wait at a bus stop as a large white and blue bus stops.
Since the people explicitly wait to board the only bus mentioned, it follows that said bus is at least close to stopping and that the location functions as a bus stop.
You wait to board a bus at a bus stop.
A bus stop is where people wait to board a bus.