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