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