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