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