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