25 pair cable's color code table. Every pair is identified by a combination of 5 tip and 5 ring colors.
Please note that CAT5 cable shown for clarity of the illustrations (tightly twisted conductors). You will see the same color code in a lesser grade cable (CAT3, voice grade) but the conductors of the pair will not be as close together and so they will be marked with small stripes of the opposite color (blue stripes on white, white stripes on blue and so on). This way you can identify the conductors as belonging to the same pair even though they are not close together in the loose bundle of wires you get after stripping the jacket off