ISA has standards for drafting the sysmbols. I suggest you look at standard ISA 5.4 and 5.5.
If the symbols is not quite of what you are looking, I suggest call the manufacturer and asked them how other engineers have represented their Coriolis flowmeter.
In our office we use the venturi symbol as a flowmeter and then we indicate on the description of that particular flowmeter what it is. (magnetic, corilis, ultrasonic, etc., brand name and model number)
We could not find anything for coriolis in ISA standards. We actually chose to show it similar to a 'U' shaped coriolis. We put a U in the pipeline with a box around the U.
That is, not the letter U, but the shape of a U in the line itself, then draw a box around it.
You can also use the symbol for a magmeter and instead of putting an "M" in the box, put a "C". Then update your P&ID lead sheet in case someone doesn't understand.