In this exact wording would invokes the future - the waiter is asking what you want in your coffee (milk,cream,sugar, etc).
It could also be used for emphasis after say you've been discussing the various merits of having coffee in various ways, and you'd put stress on the word.
How would you like you coffee?
But it still has the same meaning.
First, let's start with a declarative main clause:
It's supposed to look like this.
We'll turn it into a question by replacing this with what:
It's supposed to look like what?
But this sort of question is only allowed under special circumstances – for example, if you couldn't hear what someone said, or if you wanted to express incredulity at what they said.
Let's turn it into a normal question instead (an interrogative clause):
What is it supposed to look like ___?
We did two things here:
- We moved what to the front of the sentence, leaving behind a gap, which I've marked using an underline. Normally the gap would not be written down.
- We inverted the subject it with the auxiliary is.
We had to do step #2 because this was a main clause; main clause interrogatives are marked by subject–auxiliary inversion, unless the wh-phrase is part of the subject.
In your example, we have the same thing, except it's a subordinate clause:
Is that [ what it's supposed to look like ___ ] ?
Subordinate interrogatives are not marked by subject–auxiliary inversion, so the only thing we need to do here is move what to the front. The subject and auxiliary remain in their original order: it's, not is it.
Your version is the same thing, but it omits the subject it:
*Is that [ what ∅'s supposed to look like ___ ] ?
Here, the ∅ symbol indicates that something has been left out. However, there is nothing that would allow you to omit the subject here, so your example is ungrammatical.
In this answer, the * symbol indicates that a sentence is ungrammatical.
Best Answer
You may use this in both situations, and indeed in others; the context will make it clear which meaning is intended:
If you ask before you start preparing the coffee, you are asking how your hearer prefers their coffee to be prepared—Do you like it strong or weak (or possibly boiled to a black sludge)?
If you ask before or as you serve the coffee, you are asking how your hearer 'takes' their coffee—Do you want cream or sugar with your coffee?
If you ask after your hearer has started drinking the coffee, you are asking about the taste of the coffee—Is the coffee OK?
As for your answers, both are possible, as are many more: