Assalamo Alaikum Wr Wb!
Dear @abuluqman,
Both Yellow 5 and Yellow 6 are synthetic color additives. The chemicals used to synthesize these are probably mostly petroleum based.
If these colours do come from synthetic sources then they would be halal, and assuming all other ingredients used to produce the snack are from halal sources, then the snack would be classed as halal too. And Allah knows best!
Ma’assalam,  
Some references: 
http://www.eat-halal.com/halal-or-haram/question/how-about-yellow-5-and-blue-1/