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