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