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