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