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)(15,19)(16,25)(17,21)(18,20)(22,28)(23,27)(24,26) involution — undirected(2,3)(6,9)(10,12)(13,15)(14,19)(16,24)(17,23)(18,22)(20,28)(21,27)(25,26) involution — undirected(1,2,4,3)(5,7,8,11)(6,10,9,12)(13,16,17,18)(14,20,21,25)(15,22,23,24)(19,26,27,28)(1,3,4,2)(14,21)(15,22)(16,18)(19,26)(23,24)(27,28)(6,9)(10,12)(14,21)(19,27)(20,25)(26,28) 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.