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