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