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