It is worth noting that any race with 80+ xenophobe trait, it's pretty much impossible to keep pleased, and your only option is either war or containment.
What defines your option is their expansionist trait, as sooner or later they will want to get into your sphere of influence when that trait is higher than 70, so you may need to build some large military outposts in the neighbouring systems with a decent strike force ready for when war inevitably breaks up.
Below a guide for you to understand likelihood of peaceful existence:
Racial Characteristics
Xenophobia: A rating from 1-100 showing the fear of other races or governments
Diplomacy = A rating from 1-100 showing the ability to persuade other races. This is used to offset the Xenophobia of another race
Militancy = A rating from 1-100 showing the likelihood this race will choose military force to achieve its goals.
Expansionism = A rating from 1-100 showing the desire of this race to increase its territory
Determination = A rating from 1-100 showing the determination of this race to proceed with a chosen course of action despite setbacks.
Trade = A rating from 1-100 showing the willingness to trade with other races and to establish/allow trading posts
Translation Skill = -25 to +25 A modifier to communication attempts
