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