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