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