How do you a members directory list by a field "category" and then by number

Im looking to display a list of members in specific departments/categories. So there ideally would be a group of members and they would have a field that says department, then once they are registered, it would show them on a page with the departments heading.

A page for the 20 people in the IT department.

Another page for the 20 people in Accounting.

Each time someone registers, they would be assigned to a department list page.