Yes, it is unity gain stable. Figure 18 shows the curve for 0 dB of closed-loop gain vs frequency.
An interpretation of this diagram: The vertical axis is in dB. For example, for a closed-loop gain of 0 dB (or 20 dB, or any other gain in the diagram), the opamp is not unstable at any frequency. The curves just tell you that the closed-loop gains (for those gain settings) roll off / decay like that, with frequency. The higher the gain, the lower the bandwidth, so that the product gain*bandwidth is constant. It may be assumed that it is stable for G=1 (0 dB) because the datasheet specifies the behavior for that gain (it shows the curve for it). If it was unstable for G=1, you wouldn't see a curve for it, in that figure.