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