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