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