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