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