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