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)(11,16)(12,18)(13,19)(14,21)(15,17)(20,24)(22,23)(25,26)(27,34)(28,32)(29,37)(30,31)(33,39)(35,36)(38,40)(1,3)(2,6)(4,7)(5,8)(9,11,15,12)(10,16,17,18)(13,20,23,21)(14,19,24,22)(26,31)(28,34)(33,37)(36,38)(10,17)(11,12)(19,22)(20,21)(25,27,30,32)(26,28,31,34)(29,35,39,40)(33,36,37,38)(2,4)(6,7)(9,12,15,11)(10,18,17,16)(13,21,23,20)(14,22,24,19)(25,27)(26,28)(29,35)(30,32)(31,34)(33,36)(37,38)(39,40)(1,4,5,2)(3,7,8,6)(9,13,15,23)(10,19,17,22)(11,21,12,20)(14,18,24,16)(25,28)(26,32)(27,31)(29,38)(30,34)(33,35)(36,39)(37,40)(1,3)(2,7)(4,6)(5,8)(9,14,15,24)(10,20,17,21)(11,19,12,22)(13,16,23,18)(25,29,30,39)(26,33,31,37)(27,35,32,40)(28,36,34,38)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.