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