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