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