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