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