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