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