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