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