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