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