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