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