There is no option in Odoo to display your customer's name on the receipt in the point of sale. 

Anyway, there is a workaround. If you use the loyalty program in your PoS, the name of the customer will always be displayed on the receipt. 

If you do not want to use a loyalty program, you can still create a new one named "Customer : " with no point earned per $ spend, no reward rule and no points rules. 

Here is how it will look like when selecting a client in the PoS and printing the receipt 

This is a workaround to display your customer's name on the receipt.