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