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