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