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