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