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