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