I'll use the same method categories the PP fanposter did, because they were good ones.
Drafted Players (Draft): Self explanatory.
Rookies Free agents (RkFA): Includes undrafted rookie signings and drafted players who were cut, but who never played a game for another team.
Free agents (FA): Players to have played for another team, signed from free agency.
Trades (Trade): Self-explanatory
Waivers (Wav): Players claimed off waivers.
From the current Colts.com roster
54 players currently on Indy's roster have never played a single snap for another franchise.
Off topic slightly it shows Indy likes it's skill postion players drafted, it's LBs cheap off the open market and carries a massive number of DBs on the offseason roster.
Here it is for the starters*
*=Starter by my judgment/projection. Gijon got the TE2 starting spot, Lilja and Pollak/CJ (both drafted so doesn't matter which) at guard, Freeney-Brock-Foster-Mathis/Dawson (both drafted so doesn't matter which) on the DL and Wheeler getting the starting spot over Seward at OLB.
Indy likes it's players fresh. Adam Vinitieri is the only "starter" to have played a single game for another franchise. Brock, Lilja, and Drago were drafted by other teams but never played for them. Gijon, Saturday, Foster and Brackett were signed as undrafted free agents. 23 starters never to play for another team, 20 who have never been under contract with another team.
So remember, while the Colts make free agency boring, it's because they save all their excitement for the incoming rookies.