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