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