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