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