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