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