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