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