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