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