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