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