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