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