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