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