How to change the line color in seaborn lmplot

You can give arguments as key-value pairs (dictionary) to the underlying plt.plot and plt.scatter functions with line_kws and scatter_kws. So something like line_kws = {'color': 'red'} should do the job :

g = sns.lmplot(x="total_bill", y="tip",
               data=tips, line_kws={'color': 'red'})
sns.plt.show()