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