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