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