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