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