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