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