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