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