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