You had trouble finding a pic because this snake is moonlighting under two different scientific names. The other one, seemingly more commonly used, is Liophis epinephelus.
This site has a photo:
http://200.110.105.66/publnew/anbi/anfi7.htm
Here's a crappy translation of the site, since it's in Spanish
Distribution: One knows the West Venezuela and the Eastern Mountain range Colombia until the north Peru between the 2600 to 3300 m.s.n.m. This species is but frequent in flat earth and not in hills. Recognition: Well-known like "sabanera serpent", this species is easy to differentiate from the tierrera serpent (To crassicaudatus) so that the head is distinguished of the neck, the eyes are great with round pupil, the tail is long and to the bothered being it flattens the body. The coloration of the body is greenish coffee, with spots dark coffee on the flanks; towards half of the body including the tail it presents/displays a thin lateral line of dark coffee. The belly is of yellowish color cream. Unlike A. crassicaudatus this species is very fast and when attacked feeling it flees quickly; if this near a marsh does not vacillate escaping swimming. It reaches sizes up to 70 cm. Biology: It is fed on frogs that hunt during the hours of the day. The females put eggs underneath fallen trunks. Micro habitat: Terrestrial species, inhabits the humedales and the edge of gorges
-----
Eryx - All the fun of a boa in a convenient pocket size!