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