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