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