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