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