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