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