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