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