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