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