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