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