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