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