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)(11,21)(13,16)(15,29)(18,32)(20,26)(22,28)(23,36)(24,39)(25,38)(27,37)(30,33)(31,35)(34,40) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,10,14,17)(11,18,25,30)(12,16,19,13)(15,20,28,31)(21,33,38,32)(22,26,29,35)(23,24,34,27)(36,37,40,39)(9,11,22,39,16,24,15,21,14,25,29,37,13,27,28,38)(10,18,26,36,19,34,20,33,17,30,35,40,12,23,31,32)(3,8)(5,7)(9,12,14,19)(10,13,17,16)(11,23,25,34)(15,26,28,35)(18,27,30,24)(20,22,31,29)(21,36,38,40)(32,37,33,39)(2,6)(5,7)(9,13,14,16)(10,19,17,12)(11,24,25,27)(15,22,28,29)(18,23,30,34)(20,35,31,26)(21,37,38,39)(32,40,33,36)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.