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