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