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