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