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