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