One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,9)(8,10)(11,12)(13,14,18,27,17,22,16,21)(15,23,24,19,26,20,25,28)(1,2)(3,4)(5,6)(7,11)(8,10)(9,12) involution — undirected(5,7,8,12)(6,9,10,11)(13,15)(14,19)(16,24)(17,26)(18,25)(20,21)(22,28)(23,27)(2,4)(7,12)(9,11)(13,15)(14,20)(16,25)(17,26)(18,24)(19,21)(22,23)(27,28) involution — undirected(6,10)(9,11)(13,16,17,18)(14,21,22,27)(15,24,26,25)(19,20,28,23)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.