Stamps and submarine cables are both tools of communications needed to transfer information around the world. So it is not surprising that Singapore has issued quite a number of stamps (three to be exact) to commemorate the installation of SEA-ME-WE (South East Asia - Middle East - West Europe) cables. Some of the stamps are shown below. These sets are attractive because they are the rare 'circular' stamps issued, compared to the traditional square / rectangular ones. The different sets are similar, but note the boldfaced white lines denoting the cables.
Due to the nature of such international communications tools, the installation of cables is celebrated not just by Singapore, but also by the other partners linked by the submarine cables. The last stamp in this picture below is by a middle-east country. So these are actually international events commemorated by different countries.
Other than the three sets of stamps, the events are captured when a set of 'Stamps in stamps' were issued for the BangKok International Stamp Exhibition 1983.
I'm not aware if there are other submarine cables events captured by stamps in Singapore. Going forward, I don't think there would be any more such events captured by stamps, since submarine cables installations are no longer special events in light of the wide networks of such cables around the world.