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