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