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