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