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