One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,7,4,6)(9,10,14,16,13,17,12,18)(11,15,19,24,21,22,20,23)(25,26,28,32,29,33,36,31)(27,30,35,37,34,39,40,38)(1,3,5,4)(2,6,8,7)(9,11,12,20,13,21,14,19)(10,15,18,23,17,22,16,24)(25,27,28,35,29,34,36,40)(26,30,32,37,33,39,31,38)(10,16)(11,19)(12,14)(15,22)(17,18)(20,21)(26,31)(27,34)(28,36)(30,37)(32,33)(38,39) involution — undirected(1,4,5,3)(2,7,8,6)(10,17)(15,22)(16,18)(23,24)(25,28,29,36)(26,31,33,32)(27,35,34,40)(30,38,39,37)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.