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