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