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