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