One vertex per element, one color per generator, with an edge from x to x·s.
(5,6)(7,12)(8,10)(9,11)(13,14)(15,23)(16,22)(17,21)(18,20)(19,26)(24,27)(25,28) involution — undirected(1,2)(3,4)(5,7,9,8)(6,10,11,12)(13,15,17,26)(14,19,21,23)(16,25,18,24)(20,28,22,27)(5,8,9,7)(6,10,11,12)(14,20)(15,24)(16,18)(21,22)(25,26)(27,28)(2,4)(13,16)(17,18)(19,27)(20,22)(23,28)(24,25) involution — undirected(6,11)(10,12)(13,16,17,18)(14,20,21,22)(15,25,26,24)(19,28,23,27)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.