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