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