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