In chapter 12 of The Just Men of Cordova (1917) by Edgar Wallace, the author is describing a horse race:
The field was at the starting-post: “Your horse is drawn in the middle,” she said.
He put up his glasses. He could see the chocolate and green plainly enough. Sir Isaac’s—grey vertical stripes on white, yellow cap—was also easy to see. He had drawn the inside right.
The field was giving the starter all the trouble that twenty-four high-spirited thoroughbreds could give to any man. For ten minutes they backed and sidled and jumped and kicked and circled before the two long tapes. With exemplary patience the starter waited, directing, imploring almost, commanding and, it must be confessed, swearing, for he was a North-country starter who had no respect for the cracks of the jockey world.
For Sir Isaac the period of waiting had increased the tension. His hands were shaking, his glasses went up and down, jerkily; he was in an agony of apprehension, when suddenly the white tape swung up, the field bunched into three sections, then spread again and, like a cavalry regiment, came thundering down the slight declivity on its homeward journey.
A roar of voices. Every glass was focused on the oncoming field. There was nothing in it for two furlongs; the start had been a splendid one. They came almost in a dead line. Then something on the rail shot out a little: it was Timbolino, going with splendid smoothness.
“That looks like the winner,” said Horace philosophically. “Mine’s shut in.”
In the middle of the course the jockey on Nemesis, seeking an opening, had dashed his mount to one which was impossible.
He found himself boxed between two horses, the riders of which showed no disposition to open out for him. The field was half-way on its journey when the boy pulled the filly out of the trap and “came round his horses.”
Timbolino had a two-length clear lead of Colette, which was a length clear of a bunch of five; Nemesis, when half the journey was done, was lying eighth or ninth.
Actually I don't have much knowledge about the horse racing, and I searched a lot about the possible meanings of these bolded words, but I didn't get them.
Do these "colours and cap" refer to garments of the horse or clothes of the jockey?
It seems that "on its homeward journey" refers to "the field of horses", but aren't they supposed to be going to the finish line?! So what's meant by "homeward" here?
I think that "come round his horses" means "rejoin the other horses", but why did the author used "his" and why did he put it between quotation marks?