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