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)(13,14,17,22)(15,21,26,20)(16,19,18,23)(24,28,25,27)(2,4)(14,19)(15,24)(16,18)(22,23)(25,26)(27,28) involution — undirected(6,9)(10,12)(13,15,17,26)(14,20,22,21)(16,24,18,25)(19,27,23,28)(13,15,17,26)(14,21,22,20)(16,24,18,25)(19,28,23,27)(5,7,8,11)(6,10,9,12)(14,22)(19,23)(20,21)(27,28)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.