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)(11,14)(12,15)(13,16)(17,19)(18,22)(20,23)(21,24)(25,26,32,37)(27,33,38,34)(28,39,29,35)(30,36,31,40)(1,3,4,8)(2,5,6,7)(9,10)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(25,27)(26,33)(28,31)(29,30)(32,38)(34,37)(35,36)(39,40)(9,11,13,19)(10,14,16,17)(12,20,21,18)(15,23,24,22)(25,28)(26,34)(27,31)(29,32)(30,38)(33,37)(35,36)(39,40)(3,8)(5,7)(9,12,13,21)(10,15,16,24)(11,18,19,20)(14,22,17,23)(25,29,32,28)(26,35,37,39)(27,30,38,31)(33,36,34,40)(10,16)(14,17)(15,24)(22,23)(25,30,32,31)(26,36,37,40)(27,28,38,29)(33,39,34,35)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.