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