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