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