I know you can get the correct color from someplace like Scalefinishes or MCW Finishes, but then you would need an airbrush or something like the Preval Paint Sprayer (it can be found at some hardware stores like Ace or Home Depot). Another option is that Minutemanscalemodels sells the Scale Coat line of railroad colors in spray cans, but they are kind of expensive at around $15 a can, but it is another option if you want a color in a spray can. Looking on their website, to me the color Milwaukee Yellow looks kind of close. Just a note if you decide to go with the Scale Coat paint, you want to get the Scalecoat II line as it is designed for plastic models, the Scalecoat I line is for metal & wood models. The link I gave you is the Scalecoat I color, as it shows the paint chip, where the II one didn't show it.
You can find the Tamiya paint charts online, so you can see the colors in each of their paint lines.