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