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)(11,12)(13,14)(15,16)(17,18)(19,23)(20,22)(21,24)(25,26,30,27)(28,33,36,31)(29,32,38,34)(35,40,37,39)(9,11,13,16)(10,12,14,15)(17,19)(18,23)(20,21)(22,24)(26,27)(31,33)(32,34)(39,40)(10,14)(12,15)(18,20)(19,24)(25,27,30,26)(28,33,36,31)(29,32,38,34)(35,39,37,40)(1,2)(3,5)(4,6)(7,8)(9,12,13,15)(10,11,14,16)(17,20,22,18)(19,21,24,23)(25,28)(26,31)(27,33)(29,37)(30,36)(32,40)(34,39)(35,38)(1,3,4,7)(2,5,6,8)(9,11)(10,15)(12,14)(13,16)(17,21)(18,19)(20,24)(22,23)(25,29)(26,32)(27,34)(28,35)(30,38)(31,39)(33,40)(36,37)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.