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