i’ve seen alot of schools with orange sashes or orange tassels for the engineering graduates. so why is the engineering color orange?
My school’s orientation shirt for the engineering majors was the ugliest orange I have ever seen. It’s just pinkish-red specks layered on yellow specks. Looks orange from far away, but up close it’s like an explosion of clashing colors. So I would like to know the answer to this, too. 
It’s blue at my daughter’s school.
It’s mostly a tradition thing dating back to the 19th century. Some of them have a symbolic meaning, like the white for arts and letters being used originally to mimic the Oxford and Cambridge hoods. Green went to medicine because it was the color of herbs and olive went to pharmacy because it was similar to green and green was taken. I’d imagine the orange for engineering was because it is similar to the gold of the sciences, which was supposed to symbolize the wealth that the sciences begat.
Maybe because t’s a traditional engineering color in industry, see wikipedia entry on International Orange.
look up academic regalia on Wikipedia and you’ll get info on the colors, as well as descriptions of how bachelor’s master’s and PhD robes differ as well.