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)(11,17)(12,16)(13,18)(14,15)(19,21)(20,22)(23,24)(25,26,30,34)(27,31,37,40)(28,32,36,39)(29,33,35,38)(1,3)(2,4)(5,8)(6,7)(9,10)(11,13)(12,20)(14,15)(16,22)(17,18)(19,21)(23,24)(25,27)(26,31)(28,35)(29,36)(30,37)(32,38)(33,39)(34,40) involution — undirected(1,2)(3,4)(5,7)(6,8)(10,15)(11,18)(16,20)(19,24)(25,28)(26,32)(27,29)(30,36)(31,33)(34,39)(35,37)(38,40) involution — undirected(1,3)(2,6)(4,7)(5,8)(9,11)(10,13)(12,19)(14,18)(15,17)(16,23)(20,21)(22,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,38)(36,39)(37,40) involution — undirected(1,4,5,6)(2,3,7,8)(9,12)(10,16)(11,19)(13,23)(14,22)(15,20)(17,21)(18,24)(25,28)(26,32)(27,35)(29,37)(30,36)(31,38)(33,40)(34,39)(1,3)(2,4)(5,8)(6,7)(9,13)(10,11)(12,21)(14,17)(15,18)(16,24)(19,20)(22,23)(25,29,30,35)(26,33,34,38)(27,36,37,28)(31,39,40,32)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.