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