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