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