I'm not sure the cave as such is open, but you can still visit it even though there's no one there.
easiest to park at cala san vicente and then walk on the road to san vicente, say 10-15 mins along the road and then watch out for a sign on the right that says 'cueva' and then it's a 10min steep walk uphill.
else - just follow the indications and drive up. less fun though.