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