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