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