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