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