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