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