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)(13,14)(15,16)(17,18,23,24)(19,20,21,22)(25,26)(27,31)(28,32)(29,30)(33,34)(35,39)(36,40)(37,38)(1,3,6,4)(2,5,7,8)(9,10)(11,12)(13,14)(15,16)(17,19,23,21)(18,20,24,22)(26,30)(27,33)(32,38)(35,36)(2,7)(3,4)(10,14)(11,15)(17,20,23,22)(18,19,24,21)(25,27,29,33)(26,31,30,34)(28,36,37,35)(32,40,38,39)(1,4,6,3)(2,5,7,8)(9,11,13,15)(10,12,14,16)(17,21,23,19)(18,20,24,22)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,39)(37,38)(1,5)(2,3)(4,7)(6,8)(9,12)(10,15)(11,14)(13,16)(17,22,23,20)(18,19,24,21)(25,28,29,37)(26,32,30,38)(27,35,33,36)(31,39,34,40)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.