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