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