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)(15,22)(19,27)(23,26)(24,28) involution — undirected(5,7)(6,9)(8,12)(10,11)(13,14,18,20)(15,23,22,26)(16,17,25,21)(19,28,27,24)(1,2,3,4)(13,15,16,24,18,22,25,28)(14,19,21,23,20,27,17,26)(6,10)(9,11)(13,16,18,25)(14,17,20,21)(15,24,22,28)(19,26,27,23)(7,12)(9,11)(13,17,16,14,18,21,25,20)(15,23,24,27,22,26,28,19)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.