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