As of Pandas 0.18 one way to do this is to use the sort_index
method of the grouped data.
Here's an example:
np.random.seed(1)
n=10
df = pd.DataFrame({'mygroups' : np.random.choice(['dogs','cats','cows','chickens'], size=n),
'data' : np.random.randint(1000, size=n)})
grouped = df.groupby('mygroups', sort=False).sum()
grouped.sort_index(ascending=False)
print grouped
data
mygroups
dogs 1831
chickens 1446
cats 933
As you can see, the groupby column is sorted descending now, indstead of the default which is ascending.