Large puddle under my car/fluid all over inside?

I drive a 2002 mercury cougar and when i arrived at work today i noticed a large puddle of yellowish foam/liquid under my car. Upon inspection the stuff was sprayed all about the undercarriage as well. When i opened the hood the coolant reservoir cap was blown off but still intact and functional. Where it was there is a lot of the yelloy foam and the fluid was very low/almost out. I filled it with about 3 20oz water bottles and after the second one it stayed in the reservoir and none had leaked on the ground. Any help on what happened would be great and i need to know if it will be ok to drive about 50 miles home if not leaking. Thanks!