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