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