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