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