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