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