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