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