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