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