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