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