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