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