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