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