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