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