Unsuitable fit for tanh function in python

I am trying to fit a tanh function for the dataset shown below. The code has always worked, but there seem to be problems with this dataset. The displayed fit does not fit the data points at all.

I have already tried a few things but have not been able to find a solution.

import matplotlib.pyplot as plt
from scipy.optimize import curve_fit
import numpy as np

xdata = [26, -30, -60, 80, 110, 60, 40]
ydata = [53, 12.6, 15.8, 100, 102.1, 90.4, 70.2]

def tanh(x, a, b, c, d ):
    return a * np.tanh( b * x + c ) + d

p0 = [max(ydata), np.median(xdata),1,min(ydata)]
popt, pcov = curve_fit(tanh, xdata, ydata, p0, method='dogbox')

xModel = np.linspace(min(xdata), max(xdata))
yModel = tanh(xModel, *popt)

def Plot(graphWidth, graphHeight):
    fig = plt.figure(figsize=(16,9))
    ax = fig.add_subplot(111)
    ax.plot(xdata, ydata,  'D', label="data")
    ax.plot(xModel, yModel, label="fit")
    ax.legend()
    plt.show()

graphWidth = 800
graphHeight = 600

Plot(graphWidth, graphHeight)

How can I improve the fitting?