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