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)(11,18)(12,21)(13,16)(14,22)(15,17)(19,20)(23,24)(25,26)(27,29)(28,31)(30,36)(32,34)(33,38)(35,39)(37,40) involution — undirected(2,6)(3,7)(9,11,15,13)(10,16,17,18)(12,19,22,23)(14,20,21,24)(25,27)(26,32)(28,29)(30,35)(31,34)(33,39)(36,37)(38,40)(1,3,5,7)(2,4,6,8)(10,17)(12,22)(16,18)(19,23)(26,28)(27,34)(33,36)(35,40)(1,4)(2,7)(3,6)(5,8)(9,12)(10,14)(11,19)(13,23)(15,22)(16,20)(17,21)(18,24)(25,28,31,26)(27,29,34,32)(30,36,38,33)(35,37,40,39)(9,13,15,11)(10,16,17,18)(12,23,22,19)(14,20,21,24)(25,29)(26,27)(28,34)(30,37)(31,32)(33,35)(36,40)(38,39)(9,14)(10,12)(11,20)(13,24)(15,21)(16,19)(17,22)(18,23)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,39)(34,40) involution — undirectedA 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.