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