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