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