One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,7)(5,8)(9,10)(11,22)(12,18)(13,28)(14,20)(15,21)(16,24)(17,23)(19,30)(25,36)(26,37)(27,32)(29,33)(31,38)(34,40)(35,39) involution — undirected(2,6)(3,4)(7,8)(9,11)(10,16)(12,23)(13,29)(14,26)(15,25)(17,32)(18,33)(19,37)(20,34)(21,35)(22,28)(24,30)(27,39)(31,40)(36,38) involution — undirected(2,7)(3,4)(6,8)(9,11)(10,17)(12,26)(13,24)(14,23)(15,25)(16,32)(18,22)(19,35)(20,36)(21,37)(27,40)(28,33)(29,30)(31,39)(34,38) involution — undirected(2,8)(6,7)(9,12,15,14)(10,18,21,20)(11,23,25,26)(13,27,31,30)(16,33,35,34)(17,36,37,22)(19,28,32,38)(24,29,39,40)A 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.