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