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