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