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