In the school in the drama class room check the Tempest poster in the backroom. (Attention do this before you deliver the belt)
Here is my complete video guide for all optional graffiti in Episode 1.
All optional graffiti are immediately saved. You can replay Episodes (Collector mode) to find your missing graffiti.
There are always 2 graffiti which you can spray, it doesn't matter which one you spray.00:08 - Optional Graffiti #1 (Recreational Vandalism)
00:56 - Optional Graffiti #2 (I See U Saw)
01:34 - Optional Graffiti #3 (The Last Unicorn)
02:22 - Optional Graffiti #4 (Home Unimprovement)
03:44 - Optional Graffiti #5 (Rock Idol)
04:36 - Optional Graffiti #6 (Dramatis Personae)05:23 - Optional Graffiti #7 (Mulligan Stew)
06:36 - Optional Graffiti #8 (Pioneer Spirit)
07:20 - Optional Graffiti #9 (Face Your Anger)
08:10 - Optional Graffiti #10 (Lucid Writing)