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