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