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