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