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