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