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