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