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