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