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)(11,20)(12,26)(13,30)(14,19)(15,18)(16,24)(17,28)(21,38)(22,23)(25,33)(27,32)(29,36)(31,35)(34,39)(37,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,14,24)(10,16,19,20)(12,27,29,40)(13,25,15,22)(17,34,35,38)(18,33,30,23)(21,31,39,28)(26,37,36,32)(9,12,15,31,14,29,13,28)(10,17,30,36,19,35,18,26)(11,21,22,27,24,39,25,40)(16,32,23,38,20,37,33,34)(2,6)(5,7)(9,13,14,15)(10,18,19,30)(11,22,24,25)(12,28,29,31)(16,23,20,33)(17,26,35,36)(21,27,39,40)(32,38,37,34)(3,8)(5,7)(9,10)(11,23)(12,17)(13,18)(14,19)(15,30)(16,25)(20,22)(21,38)(24,33)(26,28)(27,37)(29,35)(31,36)(32,40)(34,39) 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.