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