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