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