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