It depends on how you want to formulate what is going to be the rest of the sentence, as you can use after that expression a subordinate clause introduced by “que” or an infinite clause introduced by “de” (your example); this is similar to the question you asked previously (concerning “avoir l’impresssion).

Je pense qu’on devrait donner aux clients l’impression d’être occupés.

Je pense qu’on devrait donner aux clients l’impression que l’on est occupés.

Je pense qu’on devrait donner aux clients l’impression que nous sommes occupés.

There is no difference in the meaning.