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