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)(12,25)(13,20)(14,16)(15,19)(17,22)(18,26)(23,33)(24,32)(27,34)(28,30)(29,31)(35,37)(36,40)(38,39) involution — undirected(2,6)(7,8)(10,16)(11,22)(13,15)(17,32)(21,30)(23,37)(24,28)(25,34)(26,29)(33,40)(35,39)(36,38) involution — undirected(1,3,5,4)(2,7,6,8)(9,11,14,24)(10,17,16,30)(12,23,27,38)(13,22,15,28)(18,33,31,39)(19,21,20,32)(25,35,34,40)(26,36,29,37)(9,12,14,27)(10,18,16,31)(11,23,24,38)(13,26,15,29)(17,33,30,39)(19,25,20,34)(21,35,32,40)(22,36,28,37)(1,4,5,3)(2,7,6,8)(9,13,14,15)(10,19,16,20)(11,22,24,28)(12,26,27,29)(17,21,30,32)(18,25,31,34)(23,36,38,37)(33,35,39,40)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.