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