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