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