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