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