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