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