diff -up src/sage/graphs/graph_generators.py.orig src/sage/graphs/graph_generators.py
--- src/sage/graphs/graph_generators.py.orig	2018-10-17 17:13:47.000000000 -0600
+++ src/sage/graphs/graph_generators.py	2018-10-25 14:04:50.496901422 -0600
@@ -911,7 +911,7 @@ class GraphGenerators():
         else:
             enc_kwargs = {'encoding': 'latin-1'}
 
-        sp = subprocess.Popen("geng {0}".format(options), shell=True,
+        sp = subprocess.Popen("nauty-geng {0}".format(options), shell=True,
                               stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE, close_fds=True,
                               **enc_kwargs)