Kalle, a rarely as we disagree, I have to also disagree with using colors, for the exact, and well stated, reasons offered by Punter. I believe it is much better to use Offense/Defense, Kicking Team/Receiving Team, Passing Team/Return Team, Fumbling Team/Return Team. On routine scrimmage plays with no change of team possession, this is rarely a problem. But, when there is a change of team possession during the down, and on kicking downs, we need to know those true descriptions, because penalty enforcement for each foul is dependent upon the team that committed it.
I had a situation recently in which an return (intercepting) team had three live-ball fouls during the same down - one prior to the interception, and two afterward. One guy on my crew failed to use the proper description, and it seemed like we had fouls by both teams, so I was trying to figure out if "clean hands" applied. After a few moments of trying to figure things out, the one guy re-reported that his foul was by [team name]. With that, I realized all three fouls were by the return (intercepting) team, so there was only the decision about which of those to accept, which turned out to be offside, to give the ball back to the passing team, penalize, and repeat the down. The penalties for the other fouls would have required allowing the return (intercepting) team to keep the ball, which were obviously not going to be accepted.
It would have helped immensely if he had initially reported that his foul was by the return team, during the return.
The CCA manuals permit the use of a jersey color (or offense/defense, etc.) when reporting a foul. But I highly recommend avoiding the use of a jersey color.
As much as anything, though, don't report and run away. Stay nearby, in case the R needs more info from you.
Robert