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