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