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