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