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