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