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