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