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