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