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