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