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