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