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