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