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