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