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