diff -up src/sage/graphs/graph_generators.py.orig src/sage/graphs/graph_generators.py
--- src/sage/graphs/graph_generators.py.orig	2019-06-26 14:41:04.000000000 -0600
+++ src/sage/graphs/graph_generators.py	2019-06-27 11:37:46.100759559 -0600
@@ -907,7 +907,7 @@ 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)