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)(14,18)(15,22)(19,21)(24,28) involution — undirected(5,7,9,6)(8,11,12,10)(13,14,16,18)(15,23,22,20)(17,19,25,21)(24,27,28,26)(2,4)(5,8,9,12)(6,10,7,11)(14,19)(17,25)(18,21)(20,26)(23,27)(24,28)(2,4)(6,7)(10,11)(13,15)(14,20)(16,22)(17,24)(18,23)(19,26)(21,27)(25,28) involution — undirected(15,22)(20,23)(24,28)(26,27) 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.