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