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