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