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