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