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