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