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