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