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