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