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