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