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