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