Place coleslaw in a large bowl. Combine mayonnaise, vinegar, sugar, mustard, and 1/4 teaspoon each of salt and pepper, stirring with a whisk. Pour mayonnaise mixture over coleslaw, tossing well to coat coleslaw. Cover and chill until ready to serve.
Combine ground beef, Worcestershire sauce, onion, and remaining 1/2 teaspoon each of salt and pepper. Divide into 8 equal portions; shape each into a 1/2-inch-thick patty.
Place patties on a grill rack coated with cooking spray, and grill 5 minutes on each side or until done.
Place 1 burger patty on bottom half of each bun; top each patty with 1/4 cup slaw. Place top halves of buns on burgers.