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