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