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