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