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