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