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