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