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)(15,23)(16,26)(19,28)(20,24) involution — undirected(6,9)(7,11)(13,14)(15,24)(16,19)(17,21)(18,27)(20,23)(22,25)(26,28) involution — undirected(2,4)(13,15,25,26,17,23,18,16)(14,19,27,20,21,28,22,24)(6,9)(10,12) involution — undirected(5,7,8,11)(6,10,9,12)(13,16,18,23,17,26,25,15)(14,20,22,19,21,24,27,28)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.