We spoke with the actress at Pamella Roland's Spring/Summer New York Fashion Week show .
Roland designed Williams' costume wardrobe for The Devil Wears Prada , which is gearing up for its London run in October.
The star filled us in on how she takes care of her voice while doing eight performances a week and how she winds down after a show.
She said she likes to grab a meal with friends in town who are there to see her and get a drink.
What are her favorite cocktails for the season?
Watch to find out.