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