Maybe the same suit, with a light jacket and trousers or skirt, but skirt longer then your knees. There are lots of suits of light colours with you can accesorize with elegant scarf, sunglasses, belt or hat etc.
And I don't mean office type of suit which is too much simple. Or you can go for smth in "marine" theme, like whites, red and blues. Its can match the event. And shoes also depends will you stand or sit and what is the plan for event. Check the plan for event.. and enjoy it!
P.S. I always choose the skirt longer then your knees when are you sitting..))) so you will feel yourself more comfortable.