Today is Monday!

Because they took a rest on weekend well.

(Not sure what you mean. Maybe 'Because they rested well on the weekend?')

I'm afraid of Monday too.

But i got up at 6 am this morning and then arrived at my company at 7 am.

After working of (in the) morning, I went to a Starbucks with my junior _____.

(junior what? junior partner? do you mean with a younger workmate?)

We drunk (drank) a coffee and had a Panini.

She talked  (to me) about the other co-worker's attitude to me while eating.

(since 'talk to me' is an expression, it's better to put it together)

I thought My junior has some complaints to other coworker.

I thought my junior had some complaints about the other coworkers. (if they were complaining about only one coworker, then it would be 'had some complaints about another coworker.')

I couldn't say nothing to her.

(in spoken language it's ok to use double negative, but in writing try to avoid it, so correct would be: 'could say nothing to her' or 'couldn't say anything to her')

Because we must save our breath in the company.

(not sure that's the expression you want. Dictionary definition here: http://dictionary.cambridge.org/dictionary/english/save-your-breath)

After working, I will have dinner for Pasta.

(pasta for dinner)

And then, I'm going to work out at 9 pm.

Your Mondays sound very busy. I'd probably dislike Mondays if I was you too.