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