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