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