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