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