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