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