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