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