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