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