One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,11)(8,10)(9,12)(13,14,17,20,16,18,24,25)(15,21,23,28,22,19,26,27)(5,7)(6,9)(8,12)(10,11)(14,18)(19,21)(20,25)(27,28) involution — undirected(1,2,3,4)(15,22)(19,21)(23,26)(27,28)(7,12)(9,11)(14,18)(19,21)(20,25)(27,28) involution — undirected(6,10)(9,11)(13,15,17,23,16,22,24,26)(14,19,20,27,18,21,25,28)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.