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