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