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