To file your I-485, you need only a copy of I-140 approval notice
Excerpt from instructions for Form -485:
"Evidence of eligibility. -- Based on an immigrant petition. Attach a copy of the approval notice for an immigrant petition which makes a visa number immediately available to you,..."
"Employment-Based Applications
If you are filing based on an offer of permanent emploument in the United States, you should submit the following:
.i-485
.G-325A
.Copy of your I-797, Notice of Action, if your I-140 has been approved
.........."