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