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