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