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