Yes, foreign passport holders who are 21 years or older are allowed to play Toto in Singapore without being a Permanent Resident or Singaporean citizen. Anyone who is of a legal age is eligible to participate.
However, if you win, you will need to claim the prize money in the country. For foreigners who are interested in playing Toto via an online Singapore Pools account, you will need to register and hold a valid Foreign Identification Number (FIN).