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