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