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