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