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