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