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