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