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