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