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