Buttermilk Coleslaw

This is a big recipe.  It will serve 36 people or more.

3 cups mayo
9 tablespoon Dijon mustard
12 tablespoons light brown sugar
12 tablespoons apple cider vinegar
12 tablespoons buttermilk
3 teaspoons celery salt
6 teaspoons kosher salt
6 teaspoons pepper
24 cups finely shredded green cabbage about 4 heads
24 cups finely shredded purple cabbage about 4 heads
12 large carrots, shredded

 Whisk together mayo, mustard, sugar, vinegar, buttermilk, celery salt, kosher salt, and pepper in a large bowl.  Add to cabbage and carrot.