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)(15,23)(16,20)(17,26)(18,22)(19,24)(21,27)(25,28) involution — undirected(1,2)(3,4)(6,9)(10,12) involution — undirected(2,4)(13,15,18,16)(14,19,22,28)(17,25,27,24)(20,26,23,21)(2,4)(13,16,18,15)(14,20,22,23)(17,25,27,24)(19,26,28,21)(5,7,8,11)(6,10,9,12)(15,16)(19,28)(20,23)(24,25)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.