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