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