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)(11,12)(13,15)(14,21)(16,18)(17,22)(19,24)(20,23)(25,26)(27,34)(28,29)(30,33)(31,37)(32,38)(35,40)(36,39) involution — undirected(1,2,4,6)(3,5,8,7)(9,11,15,16)(10,12,13,18)(14,19,22,23)(17,20,21,24)(25,27)(26,31)(28,35)(29,36)(30,37)(32,39)(33,34)(38,40)(1,2)(3,5)(4,6)(7,8)(9,12,15,18)(10,16,13,11)(14,20,22,24)(17,23,21,19)(25,28,30,32)(26,29,33,38)(27,35,37,39)(31,36,34,40)(1,3,4,8)(2,5,6,7)(9,12)(10,11)(13,16)(14,20)(15,18)(17,19)(21,23)(22,24)(25,29,30,38)(26,32,33,28)(27,36,37,40)(31,39,34,35)(9,13,15,10)(11,18,16,12)(14,21,22,17)(19,24,23,20)(25,26)(27,31)(28,29)(30,33)(32,38)(34,37)(35,36)(39,40)(9,14,15,22)(10,17,13,21)(11,19,16,23)(12,20,18,24)(25,27)(26,31)(28,35)(29,36)(30,37)(32,39)(33,34)(38,40)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.