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