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