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