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