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