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