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