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)(15,16)(17,18)(20,27)(22,28)(23,26)(24,25) involution — undirected(1,2,3,4)(5,7,9,8)(6,10,11,12)(13,14,22,25,20,24,17,21,19,16,18,23,27,26,28,15)(2,4)(5,8,9,7)(6,10,11,12)(13,15,17,24,27,23,22,14,19,21,28,26,20,25,18,16)(6,11)(10,12)(13,16,18,25,20,26,28,21,19,14,22,23,27,24,17,15)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.