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