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