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