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