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)(15,19)(16,22)(17,23)(18,25)(20,27)(21,24)(26,28) involution — undirected(13,15,24,26,17,27,16,25)(14,18,22,20,23,28,21,19)(6,9)(10,12)(13,15,17,27)(14,19,23,20)(16,25,24,26)(18,21,28,22)(2,4)(5,7,8,11)(6,10,9,12)(13,15,17,27)(14,20,23,19)(16,26,24,25)(18,21,28,22)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.