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