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