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)(25,26,31,27)(28,35,38,32)(29,33,30,34)(36,40,37,39)(1,2)(3,4)(5,7)(6,8)(11,17)(15,21)(18,23)(22,24)(26,27)(32,35)(33,34)(39,40) involution — undirected(1,3)(2,6)(4,7)(5,8)(10,14)(15,21)(16,19)(22,24)(25,27,31,26)(28,35,38,32)(29,34,30,33)(36,40,37,39)(1,4,5,6)(2,3,7,8)(9,10)(11,15)(12,16)(13,14)(17,21)(18,22)(19,20)(23,24)(25,28)(26,32)(27,35)(29,36)(30,37)(31,38)(33,39)(34,40)(1,4)(2,3)(5,6)(7,8)(9,11)(10,15)(12,18)(13,17)(14,21)(16,22)(19,24)(20,23)(25,29,31,30)(26,33,27,34)(28,36,38,37)(32,39,35,40)(1,2)(3,4)(5,7)(6,8)(9,12)(10,16)(11,18)(13,20)(14,19)(15,22)(17,23)(21,24)(25,30,31,29)(26,34,27,33)(28,37,38,36)(32,40,35,39)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.