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