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