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