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