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