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