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