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