Follow the coast road north out of Gisborne for about 10 kms until you come to Tatapouri Beach. Towards the northern end of the beach, turn right onto Makorori Road, and park anywhere convenient along it on the grass beside the beach.
Be aware that these cliffs are actively eroding, especially during or after rain. They are at a relatively low angle at the southern end (which is therefore the safest place to explore the boulders at the base), but steeper and more hazardous around the headland further north, where you will see evidence of large rockfalls abd block slides.
An easy walk along the beach for a few hundred metres.