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